Chapters 9 and 10: Muscular System Anatomy and Physiology Flashcards
Types of contraction (at least the three basic ones; what are they, what is happening with the muscles during each of these different contractions?)
- Muscles can remain the same length when they contract:
Isometric contraction,
try pushing against a wall
- Muscles can shorten when they contract:
Concentric contraction,
the up phase of biceps curl (watch Muscles pull in supplemental materials)
- Muscles can extend when they contract:
eccentric or lengthening contraction:
down phase of a biceps curl
Muscles work as a team: Do you know which muscles are the agonist/synergist/antagonist in a biceps curl? What do these words mean in terms of muscle contraction?
• Agonist: muscle that, when it contracts, causes an action
• Antagonist: a muscle working in opposition to agonist
Example: the biceps brachii can be used to lift weights and is the agonist, while the triceps is the antagonist but when you move a bowling ball back to prepare to bowl, the biceps is the antagonist and the triceps the agonist.
• Synergists: muscles that work together to cause a movement
- *Prime mover:** plays major role in accomplishing movement. When extending your arm the prime mover is the triceps, when flexing is the biceps.
- *• Fixators: ** stabilize joint/s crossed by the prime mover; prevent movement of the origin of the prime mover.
BICEP CURL: Agonist - Prime mover muscle: Biceps; Antagonist - Opposing muscle group: Triceps. Synergist - Helping muscle group(assists): Brachioradialis; Fixators - Prevents unnecessary movement: Abs and Back, and Shoulders, and wrists..
Major functions of muscles (remember that many functions are beyond contraction and movement)
• Antigravity
• Antioxidants defense
• Bone mass
• Bone strength
• Blood pressure control
• Breathing
• Locomotion
• Movements
• Strength
• Flexibility
• Metabolism
• Weight control
• Obesity Prevention
• Diabetes Prevention
• Heat Production
• Protein synthesis
• Hormonal regulation
• Immune system
• Overall performance
• Endurance
• Prevention of mental, psychological & psychiatric disorders
• Prevention/limitation
of sarcopenia and aging
frailty/weakness/falls
Muscle Health and Disease: Why are muscles so important for overall health? What are some of the metabolic diseases that occur if our muscles are not healthy/exercised?
Sarcopenia (muscle atrophy and muscle weakness)
Diseases Related To The Loss of
Muscle Function/Repair:
Muscular Dystrophies (sarcolemmal)
Malignant Hyperthermia (RyR and DHPR)
Muscular dysgenesis (DHPR)
Central Core Disease (RyR)
Brody disease (Ca+2 pumps)
Nemaline myopathy (Skeletal TnT)
Several myopathies (sarcomeric proteins)
Centronuclear myopathies
Charcot Marie Tooth (CMT) syndromes (MTMR proteins)
Cardiomyopathies (Troponins)
Muscle Wasting with Aging (Sarcopenia): What is sarcopenia? When does it start? How can it prevented/treated?
- Health males: from 35-60 years, average loss of 3-6 kg of muscle mass and an equivalent gain of abdominal fat. Muscle wasting increases after the 6th decade of life and particularly during the 7th decade of life. In women this can even be worst as women start at a significantly lower peak muscle mass levels in adulthood
- By the 7-8th decade of life humans can lose as much as 50-70% of muscle mass
- Among older adults (those 65 or older), falls are the leading cause of injury death. They are also the most common cause of nonfatal injuries and hospital admissions for trauma
- Mental and psychiatric disorders and suicide rates increase exponentially as elderly lose independence
- Leg muscle weakness has been shown to increase the risk of falls in the elderly four-fold.
- Grip strength in middle age is associated with disabilities in old age
Nerve-Muscle Interaction: What are the different levels from the brain to the muscle cell where diseases can occur? What are some examples of muscle cell disease?
Central Nervous System: Infection(Lyme, Polio, Chagas, HIV, Botulism):CFS, Depression, Drugs, CMTs) - Motor neuro disorders: amyotrophic lateral sclerosis, primary lateral sclerosis,
progressive pseudobublas palsy, progressive muscular atrophy, progressive bulbar palsy
Muscular dystropheies (MDX), Myopathies (mitochondrial), Channelopathies, CMTs
Peripheral Nerve: Congenital and familial Myasthenia gravis (MG), drug-induced MG, Limb-Girdle MG.
Basics of Muscle Structure (layers of connective tissue, from the muscle level to the sarcomere level, basic structure of the sarcomere)
Excitation/contraction coupling: Do you know the phases (from nerve action potential to calcium being pumped back to the sarcoplasmic reticulum)? What is the difference between the motor neuron action potential and muscle cell action potential in terms of their effects?
You must know that the nerve ending at the NMJ has its own action potential that leads to the release of the neurotransmitter Acetylcholine (Ach), which in turn binds to the Acetylcholine Receptors (Nicotinic acetylcholine receptors, or nAChRs, or simply AchRs) on the muscle cell membrane (sarcolemma); this binding opens the channel, sodium ions (Na+1) now enter the muscle cell leading to depolarization of the sarcolemma (muscle cell action potential).
Sarcomere structure and function: Troponin C, Tropomyosin, Actin, and Myosin. What is the sliding theory of contraction? What are cross bridges? What is the role of calcium?
Tropomyosin protiens lie on two sides of the actin myofilament
Globular Troponin C proteins are attached to the Tropomyosin.
Calcium binds to the Troponin C proteins changing its shape and moves Tropomyosin and leaving it open for mysion heads to attach to the binding site on the action to from a roll of cross bridges which help muscle contration
Force-Length Relationship: Who developed this theory? Why muscles that are either shortened or overstretched do not produce optimal levels of force? Why at the ideal sarcomere length (with stretching) you can get more force out of your muscle?
DR. Guillaume-Benjamin-Amand Duchenne de Boulogne
Muscle length 2 because there is and optimal overlap of actin and myosin myofilaments, so the number of crossbridges tat can form is maximal.
Force-Frequency Relationship (Twitch vs. tetanus): So you optimally stretched your muscle? How can you get more force? Why does muscle force increase upon increased frequency of stimulation? What is the cellular mechanism? What are some of the basic differences between a twitch, an unfused tetanus, and a tetanic force?
Basis of muscle metabolism, ATP sources: From the cytosolic pool of ATP generated by action of an enzyme called creatine kinase on creatine and ADP, some ATP is formed. How long does it last with intense exercise? Why becoming aerobic could be beneficial for weight loss/control? Who can give you more ATPs, aerobic or anaerobic respiration? From an energy point of view, why are muscles so important?
Creatine phospate= fast
Anaerobic respiration = sprint
Anerobic respiration = long term exersice
